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  • Cynthia M. Johnson, MA
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Endometrial tissue is normally found in the uterus. Endometriosis is when this type of tissue is found outside the uterus on the organs in the belly or pelvis. Endometrial tissue thickens and sheds when estrogen is present. It leaves the body during menstruation.

Tissue that forms outside of the womb will also thicken due to estrogen changes. However, it cannot pass out of the body during menstruation. This causes swelling and scarring in the belly and pelvis.


Nucleus Medical Media Imagehttp://services.epnet.com/getimage.aspx?imageiid=24512451si1983.jpgEndometrial LesionsNULLjpgEndometrial LesionsNULL\\filer01\Intellect\images\si1983.jpgCopyright © 2002 Nucleus Communications, Inc. All rights reserved.16NULL2002-10-012553912451_11876Copyright © Nucleus Medical Media, Inc.


The cause of endometriosis is not known. It may be due to:

  • Menstrual tissue that backs up through the fallopian tubes and spills into the belly
  • An immune system that does not stop tissue from implanting on other organs
  • A lymph system that carries cells from the uterus
  • Surgery that accidentally relocates cells

Risk Factors

Endometriosis is more common in women of reproductive age. Other things that may raise the risk are:

  • Menstruating before the age of 10 years old
  • Having a cycle of less than 28 days
  • Having a flow of more than 5 to 6 days
  • Having an abnormal reproductive tract
  • Not having children


Some people do not have problems from endometriosis. Others may have mild to severe problems, such as:

  • Cramping and pelvic pain before and during menstrual bleeding
  • Pain during sex and bleeding after
  • Pain during bowel movements or urination
  • Irregular menstrual cycles
  • Pain in the lower back, belly, or pelvis


The doctor will ask about symptoms and health history. A pelvic exam will be done.

Pictures will be taken of the pelvis. This can be done with an ultrasound taken from the outside of the belly. It may also be done with a probe placed in vagina.

Surgery is needed to confirm the diagnosis. This can be done with a laparoscopy. During surgery, a sample of tissue may be taken for testing. This can be done with a biopsy.


Treatment depends on how severe the problems are. The goals are to ease pain and slow tissue growth. Options may be:


There are no steps to prevent endometriosis.





  • Endometriosis. ACOG website. Available at: https://www.acog.org/Patients/FAQs/Endometriosis.
  • Endometriosis. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/endometriosis.
  • Endometriosis. Office on Women's Health—US Health and Human Services website. Available at: https://www.womenshealth.gov/a-z-topics/endometriosis.
  • Levine EM, et al: Deep Infiltrating Endometriosis: Making the Diagnosis. J Diagn Med Sonogr 2019;35(4):1-3.
  • 2/12/2018 DynaMed Systematic Literature Surveillance https://www.dynamed.com/condition/endometriosis: Guerriero S, Saba L, et al. Transvaginal ultrasound (TVS) versus magnetic resonance (MR) for diagnosing deep infiltrating endometriosis: a systematic review and meta-analysis. Ultrasound Obstet Gynecol. 2017 Nov 20.


  • Beverly Siegal, MD, FACOG
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.